1. Field of the Invention
The present invention relates to a camera having a visual line detection device, and more particularly to a camera which assigns priority to photography when a release operation is performed during the input of calibration information for determination of the visual line of a photographer.
2. Description of the Related Art
Cameras are known which have a visual line detection device to determine the visual line of a photographer. For example, a camera is disclosed in Japanese Laid-Open Patent Publication No. 1-274736 ("JP-A-1-274736") in which the visual line of a photographer is determined by a light beam which shines on the eyeball of a photographer looking into a viewfinder. The light is reflected from the cornea, and the whole eyeball is imaged on a CCD area sensor by a condensing lens. The center position of the pupil and the position of the reflected light are then determined from this image. A region within the viewfinder which the photographer is scrutinizing may be detected by calculating the angle of rotation of the eye based upon the information obtained from the image of the eyeball.
Errors in the calculated visual line tend to arise when average values are used to calculate the visual line of the photographer, and individual differences between photographers are ignored. For example, the size of the eyeball and the visual axis of the eyeball may differ between photographers. Further, the visual line of a photographer is affected when contact lenses or spectacles are worn when looking through the viewfinder, as opposed to when a "naked eye" is used to look through the viewfinder. Therefore, in order to prevent errors from arising when calculating a visual line, the known cameras having a visual line detection device input information relating to the eyes of respective individual photographers into the camera before calculating a visual line.
For example, the input information relating to the eye of a photographer may be performed according to techniques described in a Japanese brochure for the Canon EOS 5 camera, or in the Japanese publication "CAMERAMAN", October, 1992, page 24. These techniques are described below.
(1) A calibration mode on a mode selection dial is selected, and a selected calibration number is set. For example, if there are five calibration numbers, calibration data related to five people can be input into the camera. When the calibration mode is selected a first reference mark blinks at a first position within the viewfinder.
(2) While looking into the viewfinder and scrutinizing the first reference mark, the photographer half depresses a release button. A CCD area sensor images the photographer's eyeball at this time and stores the image information in memory.
(3) When the half depression of the release button is discontinued, the first reference mark is extinguished. A few seconds later, a second reference mark blinks at a second position within the viewfinder.
(4) While looking into the viewfinder and scrutinizing the second reference mark, the photographer half depresses the release button. The CCD area sensor images the photographer's eyeball at this time and stores the image information in memory.
(5) Based upon the output signals obtained from the CCD when the first and second reference marks were scrutinized, information relating to the photographer's eyeball is calculated and stored in memory.
However, the known cameras having a visual line detection device suffer from the drawback that there is a risk of missing a chance to take a photograph because the shutter does not operate during the calibration mode operation, even if the release button is fully depressed.